Metallocenes, polymerization catalyst systems, their preparation, and use

ABSTRACT

Metallocenes having a 9-fluorenyl group and another cyclic dienyl group connected by a single carbon having a terminally unsaturated hydrocarbyl substituent wherein the 9-fluorenyl group has a hydrocarbyl substituent in the 4 position, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.

This application is a division of application Ser. No. 09/317,300, filedMay 24, 1999, now U.S. Pat. No. 6,291,382, the disclosure of which isincorporated herein by reference.

This invention relates to certain metallocenes. In another aspect thisinvention relates to the polymerization of olefins. In another aspectthis invention relates to metallocene based catalyst systems for thepolymerization of olefins.

BACKGROUND OF THE INVENTION

The discovery that metallocenes of transition metals can be used ascatalysts for the polymerization of olefins has led to significantamounts of research since it was found that different metallocenes couldproduce different types of polymers. One of the earliest references tothe use of metallocenes in the polymerization of olefins is U.S. Pat.No. 2,827,446 which discloses a homogeneous, i.e. liquid, catalystsystem of bis(cyclopentadienyl) titanium dichloride and an alkylaluminum compound. The activity of such systems was not, however, ashigh as would be desired. It was latter discovered that more activecatalyst systems would result if the metallocene was employed with analkylaluminoxane cocatalyst, such as that disclosed in U.S. Pat. No.3,242,099.

U.S. Pat. Nos. 5,498,581 and 5,565,592 revealed a particularlyinteresting class of new metallocenes that are suitable for use in thepolymerization of olefins, namely bridged metallocenes having aterminally unsaturated group extending from the bridge. One particularlypreferred metallocene of that type was the metallocene which can becalled1-(9-fluorenyl)-1-(cyclopentadienyl)-1-(methyl)-1-(but-3-enyl)methanezirconium dichloride. The metallocenes of that type were found to beparticularly desirable in that they allowed for the production of solidcatalyst systems that could be employed effectively in slurrypolymerization processes.

The present invention is based on the subsequent discovery thatfluorenyl containing metallocenes which have a bridge with a terminallyunsaturated group and also a hydrocarbyl substituent on the 4 positionof the fluorenyl group produce unexpected benefits.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a bridgedmetallocene in which two cyclodienyl-type groups are connected by asingle carbon bridge which contains a terminally unsaturatedsubstituent, one of the cyclodienyl groups being a 9-fluorenyl radicalhaving hydrocarbyl substitution at the 4 position. In accordance withanother aspect of the present invention there is provided olefincatalyst compositions comprising such metallocenes and a suitablecocatalyst. In accordance with yet another aspect of the presentinvention there is provided a process for polymerizing olefins usingsuch catalyst systems.

DETAILED DESCRIPTION OF THE INVENTION

The metallocenes of the present invention include those represented bythe formula R(Z)(Z)MQ_(k) wherein each Z bound to M and is the same ordifferent and is a cyclodienyl-type ligand selected from substituted orunsubstituted cyclopentadienyl, indenyl, tetrahydroindenyl,octahydrofluorenyl, and fluorenyl ligands; with the further proviso thatat least one Z is a 9-fluorenyl having a hydrocarbyl substituent at the4 position, R is a structural bridge linking the Z's which is a singlecarbon atom connecting the Z's and which has its other valencessatisfied by a terminally unsaturated hydrocarbyl substituent,preferably having 2 to 20 carbon atoms, and by hydrogen or a hydrocarbylgroup, preferably having 1 to 10 carbon atoms, and M is a metal selectedfrom the group consisting of IVB, VB, and VIB metals of the periodictable, each Q is the same or different and is selected from the groupconsisting of hydrogen, halogens, and organo radicals; k is a numbersufficient to fill out the remaining valances of M.

A particularly preferred type of bridged metallocene includes those inwhich the olefinically unsaturated substituent has the formula

wherein R″ is a hydrocarbyl diradical having 1 to 20 carbon atoms; morepreferably 2 to 10; n is 1 or 0, and each R′ is individually selectedfrom the group consisting of organo radicals, most preferably alkylradicals, having 1 to 10 carbon atoms and hydrogen. Most preferably R″has at least two carbons in its main alkylene chain, i.e. it is adivalent ethylene radical or a higher homolog thereof.

The present invention thus envisions bridged metallocenes prepared fromvinyl terminated branched bridged ligands of the formula

wherein n is a number typically in the range of about 0 to 20; morepreferably 2-10; wherein R′ is selected from hydrogen, or organo groupshaving 1 to 10 carbons and R′″ is selected from hydrogen or hydrocarbylradicals having 1 to 20 carbon atoms. Currently preferred R′ componentsare hydrogen or alkyl groups typically having 1 to 10 carbon atoms, oraryl groups typically having 6 to 10 carbon atoms. Each Z is acyclodienyl-type radical as described earlier.

The metallocenes of such olefinically unsaturated branched-bridgedligands can be prepared by reacting the olefinically branched-bridgedbis(cyclopentadienyl-type) ligand with an alkali metal alkyl to producea divalent ligand salt that is then reacted with the transition metalcompound to yield the metallocene, using the techniques generally knownin the art for forming such metallocenes. See, for example, thetechnique disclosed in U.S. Pat. No. 5,436,305, the disclosure of whichis incorporated herein by reference.

The necessary olefinically branched-bridged organic compounds suitablefor use as ligands for such metallocenes can be made by reacting asuitable alkenyl ketone with an alkali metal salt of acyclopentadiene-type compound such as cyclopentadiene or indene to forma 6-terminal alkenyl fulvene then reacting the fulvene with an alkalimetal salt of fluorene.

Some typical examples of metallocenes containing a substituent havingolefinic unsaturation include 1-(cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methane zirconiumdichloride;1-(cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methane zirconium dimethyl;1-(3-methyl-cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methanezirconium dichloride;1-(indenyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(phenyl)methanezirconium dichloride;1-(cyclopentadienyl)-1-(4,7-dimethyl-9-fluorenyl)-1-(pent-4-enyl)-1-(methyl)methanezirconium dichloride;1-(cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(phenyl)methanezirconium dichloride; and the like.

The inventive metallocenes are suitable for preparing catalysts for thepolymerization of olefins. Such catalyst systems are prepared bycombining at least one inventive metallocene with a suitable cocatalyst.It is also within the scope of the present invention to use two or moreof the inventive metallocenes or an inventive metallocene in combinationwith one or more other metallocenes.

Examples of suitable cocatalysts include generally any of thoseorganometallic compounds which have been found suitable as cocatalystsfor metallocenes in the past. Some typical examples includeorganometallic compounds of the metals of Groups IA, IIA, and IIIB ofthe Periodic Table. Examples of compounds that have been used in thepast as cocatalysts for metallocenes include organometallic halidecompounds, organometallic hydrides, and even metal hydrides. Somespecific examples include organoaluminum alkyl compounds such astriethylaluminum, triisobutyl aluminum, diethylaluminum chloride, ethylaluminum dichloride, ethyl aluminum sesquichloride, diethylaluminumhydride, and the like. Other examples of known cocatalysts includecompounds capable of forming stable non-coordinating counter anion suchas those disclosed in U.S. Pat. No. 5,155,080. Examples of such istriphenyl carbenium tetrakis (pentafluorophenyl) boronate andtris(pentafluorophenyl) borane. Still another example of a cocatalystwould be a mixture of trimethylaluminum and dimethylfluoroaluminum suchas disclosed in Zambelli et al, Macromolecules, 22, 2186 (1989).

There are three types of currently preferred catalyst systems. Thefirst, referred to hereinafter as Catalyst System I, is prepared byprepolymerizing the metallocene in the presence of an alkylaluminoxane,optionally in the presence of a particulate material such as silica, andthen washing out hydrocarbon soluble material to produce a solidparticulate polymerization catalyst system. The second, referred tohereinafter as Catalyst System II is prepared by contacting a carrierwith an alkyl aluminum compound and then contacting that product withwater to produce a particulate cocatalyst which is then contacted withthe metallocene to produce a particulate catalyst system, which may ormay not be subjected to prepolymerization before use in forming polymer.The third, i.e. Catalyst System III, is prepared by contacting themetallocene with a relatively insoluble solid compound havinghydrocarbyl aluminoxy groups. A currently preferred technique for makingsuch a catalyst system involves contacting a solution of aluminoxanewith a crosslinking agent, optionally in the presence of a particulatesolid such as silica, to result in a solid cocatalyst having hydrocarbylaluminoxy groups, then combining that solid with the metallocene toproduce a solid catalyst system. The production of such solidcocatalysts is disclosed in U.S. Pat. Nos. 5,411,925; 5,354,721; and5,436,212, the disclosures of which are incorporated herein byreference.

A particularly preferred embodiment involves the formation of CatalystSystem I that is particularly useful for use in slurry formpolymerization processes. Catalyst System I is prepared by combining themetallocene with an organoaluminoxane and conducting a prepolymerizationto obtain a solid which is recovered and ultimately used as the catalystsystem.

The organoaluminoxane component used in preparing the Catalyst System Iis an oligomeric aluminum compound having repeating units of the formula

Some examples are often represented by the general formula

In the general alumoxane formula R is a C₁-C₅ alkyl radical, forexample, methyl, ethyl, propyl, butyl or pentyl and “n” is an integerfrom 1 to about 50 or greater. Most preferably, R is methyl and “n” isat least 4. Aluminoxanes can be prepared by various procedures known inthe art. For example, an aluminum alkyl may be treated with waterdissolved in an inert organic solvent, or it may be contacted with ahydrated salt, such as hydrated copper sulfate suspended in an inertorganic solvent, to yield an aluminoxane. Generally the reaction of analuminum alkyl with a limited amount of water is postulated to yield amixture of the linear and cyclic species of the aluminoxane.

The first step of producing Catalyst System I involves combining themetallocene and aluminoxane in the presence of a suitable liquid to forma liquid catalyst system. It is preferred that the liquid catalystsystem be prepared using an organic liquid in which the aluminoxane isat least partially soluble. The currently preferred liquids arehydrocarbons such as hexane or toluene. Typically some aromatic liquidsolvent is employed. Examples include benzene, toluene, ethylbenzene,diethylbenzene, and the like. The amount of liquid to be employed is notparticularly critical. Nevertheless, the amount should preferably besuch as to substantially dissolve the product of the reaction betweenthe metallocene and the aluminoxane, provide desirable polymerizationviscosity for the prepolymerization, and to permit good mixing. Thetemperature is preferably kept below that which would cause themetallocene to decompose. Typically the temperature would be in therange of −50° C. to 100° C. Preferably, the metallocene, thealuminoxane, and the liquid diluent are combined at about roomtemperature, i.e. around 0 to 40° C. The reaction between thealuminoxane and the metallocene is relatively rapid. The reaction ratecan vary depending upon the ligands of the metallocene. It is generallydesired that they be contacted for at least about a minute to about 1hour or more.

It is within the scope of the invention to form the liquid catalystsystem in the presence of a particulate solid. Any number of particulatesolids can be employed as the particulate solid. Typically the supportcan be any organic or inorganic solid that does not interfere with thedesired end result. Examples include porous supports such as talc,inorganic oxides, and resinous support materials such as particulatepolyolefins. Examples of inorganic oxide materials include Groups II,III, IV or V metal oxides such as silica, alumina, silica-alumina, andmixtures thereof. Other examples of inorganic oxides are magnesia,titania, zirconia, and the like. Other suitable support materials whichcan be employed include materials such as, magnesium dichloride, andfinely divided polyolefins, such as polyethylene. It is within the scopeof the present invention to use a mixture of one or more of theparticulate solids.

It is generally desirable for the solid to be thoroughly dehydratedprior to use, preferably it is dehydrated so as to contain less than 7%loss on ignition, more preferably less than 1%. Thermal dehydrationtreatment may be carried out in vacuum or while purging with a dry inertgas such as nitrogen at a temperature of about 20° C. to about 1200° C.,and preferably, from about 300° C. to about 800° C. Pressureconsiderations are not critical. The duration of thermal treatment canbe from about 1 to about 24 hours. However, shorter or longer times canbe employed provided equilibrium is established with the surfacehydroxyl groups.

Dehydration can also be accomplished by subjecting the solid to achemical treatment in order to remove water and reduce the concentrationof surface hydroxyl groups. Chemical treatment is generally capable ofconverting most or all of the water and hydroxyl groups in the oxidesurface to relatively inert species. Useful chemical agents are forexample, trimethylaluminum, ethyl magnesium chloride, chlorosilanes suchas SiCl₄, disilazane, trimethylchlorosilane,dimethylaminotrimethylsilane and the like.

The chemical dehydration can be accomplished by slurrying the inorganicparticulate material such as, for example silica, in an inert lowboiling hydrocarbon, such as for example, hexane. During the chemicaldehydration treatment, the silica should be maintained in a moisture andoxygen free atmosphere. To the silica slurry is then added a low boilinginert hydrocarbon solution of the chemical dehydrating agent, such as,for example dichlorodimethylsilane. The solution is added slowly to theslurry. The temperature ranges during chemical dehydration reaction canbe from about 0° C. to about 120° C., however, higher and lowertemperatures can be employed. Preferably, the temperature will be about20° C. to about 100° C. The chemical dehydration procedure should beallowed to proceed until all the substantially reactive groups areremoved from the particulate support material as indicated by cessationof gas evolution. Normally, the chemical dehydration reaction will beallowed to proceed from about 10 minutes to about 16 hours, preferably,1 to 5 hours. Upon completion of the chemical dehydration, the solidparticulate material may be filtered under a nitrogen atmosphere andwashed one or more times with a dry, oxygen free inert solvent. The washsolvents as well as the diluents employed to form the slurry and thesolution of chemical dehydrating agent, can be any suitable inerthydrocarbon. Illustrative of such hydrocarbons are pentane, heptane,hexane, toluene, isopentane and the like.

Another chemical treatment that can be used on solid inorganic oxidessuch as silica involves reduction by contacting the solid with carbonmonoxide at an elevated temperature sufficient to convert substantiallyall the water and hydroxyl groups to relatively inactive species.

The specific particle size of the support or inorganic oxide, surfacearea, pore volume, and number of hydroxyl groups is not consideredcritical to its utility in the practice of this invention. However, suchcharacteristics often determine the amount of support to be employed inpreparing the catalyst compositions, as well as affecting the particlemorphology of polymers formed. The characteristics of the carrier orsupport must therefore be taken into consideration in choosing the samefor use in the particular invention. It is also within the scope of theinvention to use two or more of the dehydration techniques incombination, such as thermal dehydration followed by treatment withtrimethylaluminum.

It is also within the scope of the present invention to combine such aparticulate solid with the liquid catalyst system after it has beenformed and to carry out the prepolymerization in the presence of thatsolid.

The amount of aluminoxane and metallocene used in forming the liquidcatalyst system for the prepolymerization can vary over a wide range.Typically, however, the molar ratio of aluminum in the aluminoxane totransition metal of the metallocene is in the range of about 1:1 toabout 20,000:1, more preferably, a molar ratio of about 50:1 to about2000:1 is used. If a particulate solid, i.e. silica, is used generallyit is used in an amount such that the weight ratio of the metallocene tothe particulate solid is in the range of about 0.00001/1 to 1/1, morepreferably 0.0005/1 to 0.2/1.

The prepolymerization is conducted in the liquid catalyst system, whichcan be a solution, a slurry, or a gel in a liquid. A wide range ofolefins can be used for the prepolymerization. Typically, theprepolymerization will be conducted using an olefin, preferably selectedfrom ethylene and non-aromatic alpha-olefins, and as propylene. It iswithin the scope of the invention to use a mixture of olefins, forexample, ethylene and a higher alpha olefin can be used for theprepolymerization. The use of, a higher alpha olefin, such as 1-butene,with ethylene is believed to increase the amount of copolymerizationoccurring between the olefin monomer and the olefinically unsaturatedportion of the metallocene.

The prepolymerization can be conducted under relatively mild conditions.Typically, this would involve using low pressures of the olefin andrelatively low temperatures designed to prevent site decompositionresulting from high concentrations of localized heat. Theprepolymerization typically occurs at temperatures in the range of about−15° C. to about +110° C., more preferably in the range of about 0 toabout +30° C. The amount of prepolymer can be varied but typically wouldbe in the range of from about 1 to about 95 wt % of the resultingprepolymerized solid catalyst system, more preferably about 5 to 80 wt%. It is generally desirable to carry out the prepolymerization to atleast a point where substantially all of the metallocene is in the solidrather than in the liquid since that maximizes the use of themetallocene.

After the prepolymerization, the resulting solid prepolymerized catalystis separated from the liquid of the reaction mixture. Various techniquesknown in the art can be used for carrying out this step. For example,the material could be separated by filtration, decantation, or by vacuumevaporation. It is currently preferred, however, not to rely upon vacuumevaporation since it is considered desirable to remove substantially allof the soluble components in the liquid reaction product of theprepolymerization from the resulting solid prepolymerized catalystbefore it is stored or used for subsequent polymerization. Afterseparating the solid from the liquid, the resulting solid is preferablywashed with a hydrocarbon and then dried using high vacuum to removesubstantially all the liquids and other volatile components that mightstill be associated with the solid. The vacuum drying is preferablycarried out under relatively mild conditions, i.e. temperatures below100° C. More typically the prepolymerized solid is dried by subjectionto a high vacuum at a temperature of about 30° C. until a substantiallyconstant weight is achieved. A preferred technique employs at least oneinitial wash with an aromatic hydrocarbon, such as toluene, followed bywashing with a paraffinic hydrocarbon, such as hexane, and then vacuumdrying.

It is within the scope of the present invention to contact theprepolymerization reaction mixture product with a liquid in which theprepolymer is sparingly soluble, i.e. a countersolvent for theprepolymer, to help cause soluble prepolymer to precipitate from thesolution. Such a liquid is also useful for the subsequent washing of theprepolymerized solid.

It is also within the scope of the present invention to add aparticulate solid of the type aforementioned after theprepolymerization. Thus one can add the solid to the liquidprepolymerization product before the countersolvent is added. In thismanner soluble prepolymer tends to precipitate onto the surface of thesolid to aid in the recovery of the filtrate in a particulate form andto prevent agglomeration during drying. The liquid mixture resultingfrom the prepolymerization or the inventive solid prepolymerizedcatalyst can be subjected to sonification to help break up particles ifdesired.

Further, if desired the recovered solid prepolymerized catalyst systemcan be screened to give particles having sizes that meet the particularneeds for a particular type of polymerization.

Another option is to combine the recovered inventive solidprepolymerized catalyst system with an inert hydrocarbon, such as one ofthe type used as a wash liquid, and then to remove that liquid using avacuum. In such a process it is sometimes desirable to subject theresulting mixture to sonification before stripping off the liquid.

The resulting solid prepolymerized metallocene-containing catalystsystem is useful for the polymerization of olefins. Generally, it is notnecessary to add any additional aluminoxane to this catalyst system. Insome cases it may be found desirable to employ small amounts of anorganoaluminum compound as a scavenger for poisons. The termorganoaluminum compounds include compounds such as triethylaluminum,trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride,ethylaluminum sesquichloride, and the like. Trialkylaluminum compoundsare currently preferred. Also in some applications it may be desirableto employ small amounts of antistatic agents which assist in preventingthe agglomeration of polymer particles during polymerization. Stillfurther, when the inventive catalyst system is added to a reactor as aslurry in a liquid, it is sometimes desirable to add a particulate driedsolid as a flow aid for the slurry. Preferably the solid has been driedusing one of the methods described earlier. Inorganic oxides such assilica are particularly preferred. Currently, it is preferred to use afumed silica such as that sold under the tradename Cab-o-sil. Generallythe fumed silica is dried using heat and trimethylaluminum.

Catalyst System II is prepared by reacting an organoaluminum compoundwith a suitable carrier and then with water to produce a solid which canbe used as a cocatalyst for transition metal olefin polymerizationcatalysts.

The terms “carrier” as used herein refer to the material that results ina solid product when reacted with the organoaluminum compound and water.The carrier thus does not have to actually be a solid. It iscontemplated that the carrier can be any organic, organometallic, orinorganic compound capable of affixing the organoaluminum compoundeither through absorption, adsorption, Lewis Acid/Lewis Baseinteractions, or by reaction with hydroxyl groups of the carrier.

A wide range of materials can be used as the carrier. Generally, anymaterial that will result in a solid cocatalyst that remains insolublein the polymerization diluent during the polymerization process can beemployed as the carrier. Thus the carrier includes materials that formsolids when reacted with an organoaluminum compound and water as well assolids that are insoluble in the particular liquid diluent that ispresent during the polymerization. It is generally preferred that thecarrier be capable of yielding a particulate solid cocatalyst. Thecarrier can be a material having surface groups which are known to reactwith organoaluminum compounds or a material which is free of surfacegroups which react with organoaluminum compounds. Some examples ofmaterials envisioned for use as a carrier include starch, lignin,cellulose, sugar, silica, alumina, silica-alumina, titania, zirconia,zeolites of silica and/or alumina, magnesia, calcium carbonate, aluminumtrifluoride, boron oxide, magnesium dichloride, boric acid, activatedcarbon, carbon black, organoboranes, organoboroxines, Si(OMe)₃Me,hydrocarbyl polyalcohols, boric acid, alumina, polyethylene,polyethylene glycol, and the like. One embodiment comprises dissolvingpolyethylene in a suitable organic solvent then adding theorganoaluminum compound and then adding the water to produce a solidcocatalyst. It is generally preferred that the carrier that is reactedwith the organoaluminum compound be relatively free of water, i.e. thatit contain less than about 5 weight percent water, more preferably lessthan 1 weight percent water.

The term organoaluminum compound as used herein with reference toforming Catalyst System II, refers to compounds of the formula R_(n)AlX_(3−n) wherein n is a number in the range of 1 to 3, each R is thesame or different organo radical, preferably a hydrocarbyl radical, andeach X is a halide. Typically the organo radicals would have 1 to 12carbon atoms, more preferably 1 to 5 carbon atoms. Some examples oforganoaluminum compounds include trialkylaluminum compounds,triarylaluminum compounds, dialkylaluminum hydrides, diarylaluminumhydrides, aryl alkyl aluminum hydrides, dialkylaluminum halides, alkylaluminum dihalides, alkyl aluminum sesquihalides, and the like. Somespecific examples of such organoaluminum compounds includetrimethylaluminum, triethylaluminum, dimethylaluminum chloride,triisopropylaluminum, triisobutylaluminum, trihexylaluminum,diethylaluminum chloride, ethyl aluminum dichloride, ethyl aluminumsesquichloride, dimethyl aluminum chloride, and the like. The currentlypreferred organoaluminum compounds are the alkyl aluminum compounds,especially the trialkylaluminum compounds, with trimethylaluminum beingparticularly preferred. It is also within the scope of the presentinvention to use mixtures of such organoaluminum compounds.

The organoaluminum compound can be contacted with the carrier in asuitable manner. For example a particulate solid carrier could becontacted with a suitable gas containing the organoaluminum compound andthen contacted with a gas containing water liquid diluent.Alternatively, the carrier and the organoaluminum compound can becontacted in an organic liquid and then the resulting product contactedwith water. Preferably the organic liquid diluent is anhydrous, i.e.substantially free of water. Examples of what is meant by organic liquidinclude hydrocarbons such as heptane, octane, decane, dodecane,kerosene, cyclopentane, cyclohexane, methylcyclopentane, benzene,toluene, and xylene as well as halogenated compounds such aschlorobenzene and the like, as well as mixtures thereof. It is withinthe scope of the invention to simply admix the carrier and a liquiddiluent solution of the organoaluminum compound. Another option is toadd a solution of the organoaluminum compound to a slurry of the carrierin a liquid diluent.

The amount of liquid diluent employed can vary over a wide range.Typically the amount of liquid, including liquid accompanying the addedorganoaluminum compound, would be in the range of about 0.1 to about5000 ml/gram of carrier or more often about 5 to about 200 ml/gram ofcarrier. The amount of the organoaluminum compound relative to thecarrier can vary over a wide range depending upon the particularmaterial selected as the carrier and the particular results desired. Theamount necessary to provide the greatest yield of the most activecocatalyst for a specific carrier and a specific organoaluminum compoundcan be readily determined by routine experimentation. A typical rangefor the amount of the organoaluminum compound would be from about 0.0001moles/gram of carrier to about 1 mole/gram of carrier.

The temperature at which the organoaluminum compound and the carrier arecontacted can vary over a wide range. Typically it would be carried outat a temperature in the range of about −50° C. to about the boilingpoint of the liquid diluent, if used, more generally in the range ofabout −50° C. to about 200° C. It is currently preferred to carry outthe contacting at a temperature in the range of about 10 to about 100°C. Higher temperatures can speed up the process for producing the solidcocatalyst. Higher pressures can allow for the use of highertemperatures.

After the contacting of the carrier with the organoaluminum compound iscomplete the resulting product is contacted with water. This is the mostcritical step of producing the solid cocatalyst. The water can beintroduced in any convenient manner. For example, a slurry of water in ahydrocarbon can be added to liquid containing the reaction product orwater can just be added directly to the liquid containing the reactionproduct. Other options would include adding ice or adding a solidcontaining water. Preferably, for safety reasons the water is addedslowly while the slurry is agitated as by stirring. It is currentlypreferred to introduce the water into the slurry as a gas, preferably inan inert carrier gas such as nitrogen or argon. The introduction of thewater via an inert carrier gas has been found to result in a moreuniform distribution of the cocatalyst components on the surface of thecarrier. The temperature employed during the water addition can varyover a wide range depending upon the technique being employed but istypically in the range of about −100° C. to about 100° C. In a preferredembodiment, in which the water is added to the water via an inert gas,the gas is passed through a heated vessel containing water and is thenpassed into the vessel containing the slurry, which is also preferablyheated.

The amount of water necessary to produce the cocatalyst for CatalystSystem II can vary depending upon the particular carrier selected, theamount of organoaluminum compound employed, and the amount of groups onthat carrier which will react with the organoaluminum compound. Theoptimum amount of water to be added for a particular carrier can bereadily determined by routine experimentation. Generally the water willbe employed in an amount such that the molar ratio of added water to thealuminum of the organoaluminum compound will be in the range of about0.1/1 to about 3/1, more preferably the range for the molar ratio of thewater to the aluminum of the organoaluminum compound is in the range ofabout 0.2/1 to about 1.5/1, or even still more preferably about 0.5/1 toabout 1.2/1. The reaction time can range from a few minutes to severalhours and can often be monitored by observing the temperature and/or theevolution of gases.

After the reaction with the water has been completed, the resultingsolid product is combined with a metallocene to form Catalyst System II.In one preferred embodiment, the Catalyst System is subjected to aprepolymerization, preferably in the presence of hydrogen, before beingactually used to produce commercial scale quantities of polymer. Theprepolymerization can be conducted using the same type of monomers andconditions as described above in regard to Catalyst System I.

The metallocene can be combined with the cocatalyst in any suitablemanner. One technique involves adding the metallocene to a slurryresulting from the production of the cocatalyst, or alternatively, thesolids of the slurry can be filtered and optionally washed and thencombined with the metallocene, or the liquid of the slurry can beevaporated and the resulting solids then combined with the metalloceneto form the solid catalyst system. Typically, the metallocene catalystis combined with the solid cocatalyst in a liquid diluent, preferably aliquid diluent in which the catalyst is soluble. The resulting catalystsystem can be prepolymerized directly or it can be separated from theliquid and then prepolymerized. Such a recovered solid catalyst systemcan be washed with a hydrocarbon, preferably an aliphatic hydrocarbon,and dried, preferably under a high vacuum before being prepolymerized.

The amount of the metallocene that is combined with the inventivecocatalyst can vary over a wide range depending upon the particularcatalyst and cocatalyst selected and the particular results desired.Typically the polymerization catalyst is employed in such an amount thatthe atomic ratio of the Al of the cocatalyst to the metal of thepolymerization catalyst is in the range of about 1/1 to about 10000/1,more preferably about 10/1 to 1000/1.

The temperature at which the metallocene and the cocatalyst are combinedis not considered to be particularly critical. Typically this is done attemperatures in the range of about −50° C. to about 300° C., or morepreferably about 0° C. to about 100° C., or still more preferably about10° C. to about 80° C. Typically the catalyst system can be employedshortly after the inventive cocatalyst and the polymerization catalystare brought together.

The prepolymerization can be conducted using olefins such as thosenormally polymerized by the polymerization catalysts. The currentlypreferred olefin being ethylene either alone or in combination withalpha olefins such as propylene, butene, 1-hexene, 4-methyl-1-pentene,and the like. The prepolymerizations can be conducted under a wide rangeof conditions. Typically it is preferred to conduct theprepolymerization in a liquid diluent at temperatures in the range ofabout −15° C. to about 200° C., more typically about 0° C. to about 100°C. The amount of prepolymerization conducted can vary; however,typically would be such that the prepolymer would be in the range offrom about 1 to about 95 weight percent of the resulting prepolymerizedcatalyst system, more preferably about 5 to 80 weight percent.

In a currently preferred embodiment, a prepolymerized catalyst system isprepared by reacting the carrier with the organometallic compound in aliquid diluent, then adding the water to that slurry, then after thereaction is substantially complete adding the metallocene to the slurry,then the slurry is contacted with an olefin under prepolymerizationconditions in the presence of hydrogen to produce a prepolymerized solidcatalyst system which can be used as is in the slurry or separated fromthe liquid and dried for subsequent use in a polymerization. While thedried catalyst system can be subjected to washing with a hydrocarbonbefore being used in a subsequent polymerization, it has been noted thatmore active catalyst systems in terms of grams of polymer per gram oftransition metal result if there is no such washing step.

The catalyst systems of the present invention are particularly usefulfor the polymerization of alpha-olefins having 2 to 10 carbon atoms.Examples of such olefins include ethylene, propylene, butene-1,pentene-1, 3-methylbutene-1, hexene-1, 4-methylpentene-1,3-methylpentene-1, heptene-1, octene-1, decene-1,4,4-dimethyl-1-pentene, 4,4-diethyl- 1 -hexene, 3,4-dimethyl-1-hexene,and the like and mixtures thereof. The catalysts are also useful forpreparing copolymers of ethylene and propylene and copolymers ofethylene or propylene and a higher molecular weight olefin. Thecatalysts can also be used to produce ethylene-propylene-diene (EPDM)polymers and ethylene-propylene rubber (EPR).

The polymerizations can be carried out under a wide range of conditionsdepending upon the particular metallocene employed and the particularresults desired. Catalyst systems within the scope of this invention areconsidered to be useful for polymerization conducted under solution,slurry, or gas phase reaction conditions.

When the polymerizations are carried out in the presence of liquiddiluents obviously it is important to use diluents which do not have anadverse effect upon the catalyst system. Typical liquid diluents includepropane, butane, isobutane, pentane, hexane, heptane, octane,cyclohexane, methylcyclohexane, toluene, xylene, and the like. Typicallythe polymerization temperature can vary over a wide range, temperaturestypically would be in a range of about −60° C. to about 300° C., morepreferably in the range of about 20° C. to about 160° C. Typically thepressure of the polymerization would be in the range of from about 1 toabout 500 atmospheres or even greater. The inventive catalyst system isparticularly useful for polymerizations carried out under particle form,i.e., slurry-type polymerization conditions.

It is contemplated that the catalyst systems of the present inventioncan be employed in generally any type of polymerization where similarcatalysts have been employed in the past. The solid inventive catalystsystems are considered to be particularly well suited for slurry typepolymerization processes. The conditions employed when using thecatalyst systems of the present invention can be the same as those usedwith prior art systems. Typically when the polymerization is carried outin the presence of a liquid the polymerization will be conducted at atemperature in the range of about −50° C. to about 300° C. and thepressure will be from about normal atmospheric pressure to about 2000kg/cm². In some cases it may be desirable to add some additionalorganoaluminum compound to the polymerization vessel, such astriethylaluminum or triisobutylaluminum as a poison scavenger.

A further understanding of the present invention, its objects, andadvantages will be provided by the following example.

EXAMPLE I

A series of experiments were conducted to compare the effectiveness ofdifferent metallocenes in catalyst systems which involved combining therespective metallocenes with a cocatalyst prepared by contacting silicawith trimethylaluminum and then with an activating amount of water.

The cocatalyst was prepared by suspending 2 g of silica in 100 mL oftoluene and then adding 30 mL of a 2 molar toluene solution oftrimethylaluminum. The suspension was brought to about 40° C. and waterwas bubbled through it using a moist argon flow. The amount of wateradded was 0.75 mL. After the reaction mixture was cooled to roomtemperature, the metallocene was added. The mixture was stirred and thenfiltered and dried under a high vacuum.

The metallocenes evaluated were1-(cyclopentadienyl)-1-(9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methanezirconium dichloride,1-(cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methane zirconium dichloride, and1-(cyclopentadienyl)-1-(9-fluorenyl) methane zirconium dichloride.

The polymerizations were carried out in a 1 liter laboratory autoclave.First 500 mL of normal pentane containing 1 mL of a 1.6 molar n-hexanesolution of triisobutylaluminum was added to a 1 liter round flask andstirred for 10 min. Then 0.2 g of the solid catalyst system was added tothat solution. The resulting suspension was then transferred to alaboratory autoclave under argon and heated to 70° C. and exposed to anethylene pressure of 10 bar. The mixture was stirred for 1 hr. and thereaction terminated by releasing the pressure from the reactor. Theresults of these comparisons are summarized in the following table.

TABLE 3 Metallocene Activity (g/g Zr:hr) Mη kg/mol (Flu-C(H)₂-Cp)ZrCl₂ 36 460 (Flu-C(Me) (C₄ ⁼)-Cp)ZrCl₂ 518 350 (4MeFlu-C(Me) (C₄ ⁼)-Cp)ZrCl₂550 330

The data demonstrate that the inventive metallocene is more active forthe polymerization of ethylene in this catalyst system than were eitherof the two prior art metallocenes.

That which is claimed is:
 1. A metallocene represented by the formulaR(Z)(Z)MQ_(k) wherein each Z is bound to M and is a cyclodienyl-typeligand selected from substituted or unsubstituted cyclopentadienyl,indenyl, tetrahydroindenyl, octahydrofluorenyl, and fluorenyl ligands;with the further proviso that at least one Z is a 9-fluorenyl having ahydrocarbyl substituent having 1 to 10 carbon atoms at the 4 position, Ris a structural bridge linking the Z's which is a single tetravalentcarbon atom connecting the Z's and which has its other valencessatisfied by a terminally unsaturated hydrocarbyl substituent, having 2to 20 carbon atoms, and by hydrogen or a hydrocarbyl group having 1 to10 carbon atoms, and M is a metal selected from the group consisting of4B, 5B, and 6B metals of the periodic table, each Q is the same ordifferent and is selected from the group consisting of hydrogen,halogens, and organo radicals; k is a number sufficient to fill out theremaining valences of M.
 2. A metallocene according to claim 1 whereinone Z is a fluorenyl radical having a methyl substituent at the 4position and the other Z is selected from unsubstituted cyclopentadienylor 3-methyl cyclopentadienyl.
 3. A metallocene according to claim 2wherein the bridging carbon is bound to a terminally unsaturated alkenylradical having 3 to 10 carbon atoms.
 4. A metallocene according to claim3 wherein M is zirconium the bridging carbon is bound to a but-3-enylradical and to a methyl radical.
 5. A metallocene according to claim 4having the name1-(cyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methanezirconium dichloride.
 6. A metallocene according to claim 4 having thename 1-(3-methylcyclopentadienyl)-1-(4-methyl-9-fluorenyl)-1-(but-3-enyl)-1-(methyl)methanezirconium dichloride.